AWS EC2 IPs may have low reputation to e-mail providers, so is not recommended to send e-mails using these IPs.
Also AWS SES frequently have issues with RBLs. I wouldn't use it if you use reliable delivery. It's good for newsletters because it has low cost compared to other services and when you don't care if some e-mails are not delivered. My recommendation is to setup a VPS (from a company that has clean network) with multiple IPs if you need to send a lot of messages and use postfix relay with randmap to balance the outgoing messages between the IPs.
